Add synonym support for axis names in boundary conditions and update …

…tests (#645)

* Add synonym support for axis names in boundary conditions and update tests
* Closes Issue #643

.gitignore

@@ -133,3 +133,4 @@ venv.bak/
 *.code-workspace
 examples/output/allen_cahn.avi
 examples/output/allen_cahn.hdf
+debug

pde/grids/boundaries/axes.py

@@ -183,6 +183,14 @@ def _parse_from_dict(
         bc_data = [[bc_all, bc_all] for _ in range(grid.num_axes)]
         bc_seen = [[False, False] for _ in range(grid.num_axes)]
 
+        # replace synonymous axes names
+        for pattern, repl in grid.c._axes_alt_repl.items():  # iterate replacements
+            for ext in ["", "-", "+"]:  # iterate all variants
+                if pattern + ext in data:
+                    if repl + ext in data:
+                        raise KeyError(f"Key `{repl + ext}` is specified twice")
+                    data[repl + ext] = data.pop(pattern + ext)
+
         # check specific boundary conditions for all axes
         for ax, ax_name in enumerate(grid.axes):
             # overwrite boundaries whose axes are given

pde/grids/boundaries/local.py

@@ -511,7 +511,7 @@ def from_data(
         if isinstance(data, BCBase):
             # already in the correct format
             if data.grid._mesh is not None:
-                # we need to exclude this case since otherwise we get into a rabit hole
+                # we need to exclude this case since otherwise we get into a rabbit hole
                 # where it is not clear what grid boundary conditions belong to. The
                 # idea is that users only create boundary conditions for the full grid
                 # and that the splitting onto subgrids is only done once, automatically,

pde/grids/coordinates/polar.py

@@ -15,7 +15,7 @@ class PolarCoordinates(CoordinatesBase):
 
     dim = 2
     axes = ["r", "φ"]
-    _axes_alt = {"φ": ["phi"]}
+    _axes_alt = {"r": ["radius"], "φ": ["phi"]}
     coordinate_limits = [(0, np.inf), (0, 2 * np.pi)]
 
     _singleton: PolarCoordinates | None = None

pde/grids/coordinates/spherical.py

@@ -15,7 +15,7 @@ class SphericalCoordinates(CoordinatesBase):
 
     dim = 3
     axes = ["r", "θ", "φ"]
-    _axes_alt = {"θ": ["theta"], "φ": ["phi"]}
+    _axes_alt = {"r": ["radius"], "θ": ["theta"], "φ": ["phi"]}
     coordinate_limits = [(0, np.inf), (0, np.pi), (0, 2 * np.pi)]
     major_axis = 0
 

tests/grids/boundaries/test_axes_boundaries.py

@@ -7,7 +7,7 @@
 import numpy as np
 import pytest
 
-from pde import ScalarField, UnitGrid
+from pde import PolarSymGrid, ScalarField, UnitGrid
 from pde.grids.base import PeriodicityError
 from pde.grids.boundaries.axes import (
     BCDataError,
@@ -255,3 +255,25 @@ def setter(data, args=None):
     mask = np.ones((6, 6), dtype=bool)
     mask[0, 0] = mask[-1, 0] = mask[0, -1] = mask[-1, -1] = False
     np.testing.assert_allclose(f1._data_full[mask], f2._data_full[mask])
+
+
+def test_boundaries_axis_synonyms():
+    """Test whether we can use synonyms of the axis to set boundaries."""
+    grid = PolarSymGrid([1, 2], 3)
+    expect = grid.get_boundary_conditions({"r": "value"})
+
+    gbc = grid.get_boundary_conditions
+    assert expect == gbc({"radius": "value"})
+    assert expect == gbc({"r-": "value", "r+": "value"})
+    assert expect == gbc({"radius-": "value", "radius+": "value"})
+    assert expect == gbc({"r-": "value", "radius+": "value"})
+    assert expect == gbc({"radius-": "value", "r+": "value"})
+
+    with pytest.raises(KeyError):
+        gbc({"radius": "value", "r": "value"})
+    with pytest.raises(KeyError):
+        gbc({"r": "value", "radius": "value"})
+    with pytest.raises(KeyError):
+        gbc({"radius+": "value", "r+": "value"})
+    with pytest.raises(KeyError):
+        gbc({"r-": "value", "radius-": "value"})